Stitchbonded fabrics and methods for producing them are known, as for example from K. W. Bahlo, “New Fabrics without Weaving” Papers of the American Association for Textile Technology, Inc. pp. 51-54 (November 1965). Such fabrics are made by multi-needle stitching of various fibrous substrates with elastic or non-elastic yarns, as disclosed, for example, by the Zafiroglu in U.S. Pat. Nos. 4,704,321, 4,737,394 and 4,773,328.
Stitchbonded fabrics are versatile and have a wide variety of applications. Some fabric products, for example, covers for furniture, in particular mattress covers, call for the fabric to have good stretch and/or elastic stretch characteristics. Stitchbonded fabrics could be useful in such applications, however, many traditional stitchbonded fabrics have inadequate stretch capability. Customary stitchbonded fabrics typically have a plain and monotonously uniform appearance that can detract from a product's aesthetic appeal.
To improve stitchbonded fabric stretch, the incorporation of elastic stitching yarns has been used. Despite stitching with elastic yarns and gathering the stitched fabric in both machine direction (“MD”) and cross direction (“XD”) the amount of stretch of the gathered fabric has been limited. The limitations may result from the limited ability of the stitching yarns to stretch, constraint of the stitching pattern or, in respect to nonwoven substrates particularly, from the degrees of alignment and bonding of the substrate fibers. Stitching pattern limits stretch because the characteristic yarn angle of a stitchbonded fabric stitching pattern affects elongation. Yarn angle can depend upon the stitching thread counts per inch, the pattern notation, and spaces between adjacent stitches in the yarn notation. As concerns nonwoven substrate structures, parallel alignment of the fibers to high degrees (in the MD) tends to limit MD elongation and to promote fabric failure at low cross direction elongation when the nonwoven fibers are bonded to a relatively high degree. If the nonwoven fibers are aligned parallel to a lesser degree some additional XD stretch occurs but extension is limited by the interfiber bonding.
Selected advances in technology of stitchbonded fabrics are documented in many patents including those of D. Zafiroglu which are presently assigned to Xymid, L.L.C., such as U.S. Pat. No. 4,773,238; U.S. Pat. No. 4,876,128; U.S. Pat. No. 4,998,421; U.S. Pat. No. 5,041,255; U.S. Pat. No. 5,187,952; U.S. Pat. No. 5,247,893; U.S. Pat. No. 5,203,186; U.S. Pat. No. 5,308,674; U.S. Pat. No. 5,879,779; U.S. Pat. No. 6,407,018; U.S. Pat. No. 6,821,601; and U.S. Pat. No. 6,908,664.
A noteworthy utility for stitchbonded fabrics having desirable XD elongation and especially elastic XD elongation is that of skirts for mattress covers. A mattress cover skirt is a band of typically stretchable fabric attached to the periphery of and suspended downward from a top panel that covers the surface of the mattress. Usually the skirt is configured such that its MD is aligned with the periphery of the panel and XD corresponds to the normally narrower width of the skirt. The skirt may have some decorative function but mainly it stretches elastically to effectively hold the cover in place on the mattress. It is desirable to have mattress cover skirts with good cross direction as well as machine direction stretch properties.
Many inventions pertaining to cover skirt technology are disclosed in various patents now assigned to Xymid, L.L.C., such as U.S. Pat. No. 5,636,393; U.S. Pat. No. 5,603,132; U.S. Pat. No. 6,199,231; U.S. Pat. No. 6,272,701; U.S. Pat. No. 6,842,921; and U.S. Pat. No. 6,883,193. The entire disclosures of all U.S. patent and patent applications identified herein are hereby incorporated by reference herein.
A very interesting new type of stitchbonded fabric with remarkably good XD stretch properties uses a discontinuous substrate such that some regions of the fabric have stitches through substrate material and other regions have stitches but no substrate material. The fabric has high XD extension because the stitch-only regions can stretch without the constraint of the substrate. Stretch in these substrate-free regions depends on the characteristics of the stitches such as the stitching pattern and stitching thread extension properties.
Some methods are now being evaluated for producing stitchbonded fabrics with discontinuous substrate layers with conventional stitchbonding machines. Those methods call for using separate pieces of substrate fed to the machine inlet. The pieces are typically supplied on rolls spaced laterally apart in the XD direction so that gaps exist between adjacent pieces as the rolls unwind into the stitchbonder. The machine stitches across the full width of the feed stock thereby placing stitches in substrate material and in open spaces of the gaps between the substrate material. This is an effective but awkward operating style because the substrate pieces must be produced and handled separately. The XD widths of the separate pieces have to be managed correctly so that the small width pieces and the desired gaps fill the full width of the stitchbonding machine to obtain optimum productivity. Considerable logical planning should be used to set up each production run. Additionally a separate cutting step to provide the narrow width pieces of substrate material from wider stock widths almost inevitably creates waste. Some width of the stock material does not fit into the configuration of separate pieces of the stitchbonded fabric and must be discarded. Moreover the cutting step adds time and energy to the overall process.
Another method being considered for making discontinuous substrate stitchbonded fabrics calls for feeding a continuous integrated substrate material. Before the substrate enters the stitching section, strips of the substrate are excised in situ from the substrate layer. While this technique simplifies the logistical planning for making discontinuous substrate stitchbonded fabrics, it does not solve the waste creation problem. The material cut away as strips have little use if any and are likely to be discarded.
It is desirable to have a stitchbonded fabric that provides high stretch and and optionally elastic stretch especially in the cross direction provided by discontinuous substrate structure. A method of making such a discontinuous substrate stitchbonded fabric having superior stretch that is simple to manufacture with only minor modifications of conventional stitchbonding equipment is also much desired.